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991.
N.A. Noor Q. Mahmood M. Rashid Bakhtiar Ul Haq A. Laref 《Ceramics International》2018,44(12):13750-13756
The density functional theory based full-potential linear-augmented-plane-wave plus local-orbital method has been used to study the physical properties of PbSnO3 in hypothetical cubic perovskite. An external pressure up to 40?GPa has been applied on PbSnO3 to realize the variation in its electronic band structure and the subsequent optical properties. The stability of the PbSnO3 has been investigated by the mechanical properties, the enthalpy of formation and Goldschmidt tolerance factor. Moreover, the Born criteria have been adopted to justify the mechanical stability of the PbSnO3 perovskite. We show that the electronic bandgap of PbSnO3 can be tailored from indirect to direct band gap at high symmetry (X-X) direction at an external pressure of magnitude ~ 26?GPa. The effect of pressure on the optical properties has been studied in terms of dielectric function, absorption, refraction, reflection, and optical loss factor. The application of hydrostatic pressure has shifted the maximum absorption toward the visible range, revealing that PbSnO3 can be used for high- pressure optoelectronic applications. 相似文献
992.
K. Jenab S.M. Seyed Hosseini B.S. Dhillon 《Reliability Engineering & System Safety》2008,93(4):595-603
This paper presents an analytical approach for dynamic reliability networks used for the failure limit strategy in maintenance optimization. The proposed approach utilizes the moment generating function (MGF) and the flow-graph concept to depict the functional and reliability diagrams of the system comprised of series, parallel or mix configuration of self-healing units. The self-healing unit is featured by the embedded failure detection and recovery mechanisms presented by self-loop in flow-graph networks. The newly developed analytical approach provides the probability of the system failure and time-to-failure data i.e., mean and standard deviation time-to-failure used for maintenance optimization. 相似文献
993.
Avascular tumor growth model for multicellular spheroids is considered. The model is a moving boundary problem and consists of three types of cells. The governing equations are nonlinear hyperbolic and/or parabolic differential equations. Comparisons of the numerical solutions with the solution of the recent studies are done. The effect of the necrotic region on the tumor growth is discussed. 相似文献
994.
Mohammad Saidi-Mehrabad Mahmood Rezaei Sadrabadi Iman Mohammadian 《The International Journal of Advanced Manufacturing Technology》2008,37(1-2):191-201
As we know fuzzy modeling is one of the most powerful techniques to extract experts’ knowledge in the form of fuzzy if-then
rules. In this research work, a new method to fuzzy modeling is proposed in which the main goal is to construct a fuzzy rule-base
of the type of Mamdani. In the proposed method, fuzzy c-means (FCM) clustering is used for structure identification and two
optimization problems are used for parameter identification. The proposed method is used to simulate experts’ knowledge for
performance evaluation of tenants in incubators. The authors have implemented their proposed method in a real numerical example
successfully. 相似文献
995.
Abdul Ghafar Shah Tahir Mahmood Muhammad N. Naeem Shahid H. Arshad 《Acta Mechanica》2011,216(1-4):17-28
In this paper, vibrations of fluid-filled isotropic circular cylindrical shells are studied based on elastic foundations. The wave propagation approach is employed to solve the shell problem. This approach is formulated by approximating the eigenvalues of the characteristic beam functions. Vibrations of natural frequencies for both empty and fluid-filled cylindrical shells based on elastic foundations are evaluated and their comparisons are performed to confirm the validity and accuracy of the present method. An excellent agreement has been found between the present and previous ones available in the literature. It is observed that frequencies are strongly affected when a cylindrical shell is attached with elastic foundations. 相似文献
996.
In this research, heterogeneous cation exchange membranes were prepared by the casting‐solution technique using polycarbonate (PC) and S‐polyvinylchloride (S‐PVC) as binders along with cation exchange resin as functional group agent. The effect of blend ratio (PC to S‐PVC) of polymer binder on structure and electrochemical properties of the prepared membranes were elucidated. The morphology of the prepared membranes was investigated by scanning electron microscopy (SEM) and scanning optical microscopy (SOM). The images show that the addition of PC ratio in the casting solution results in formation of a membrane with more inner cavities and micro voids. The electrochemical properties and mechanical strength tests were conducted. Water content, ion exchange capacity, ion permeability, flux, current efficiency, and oxidative stability of the prepared membranes initially were decreased by increasing the PC ratio in the casting solution and then it began to increase. The blending of S‐PVC and PC polymers results in membranes with lower mechanical strength. Membrane potential, surface charge density, perm‐selectivity, cationic transport number, electrical resistance, and energy consumption were initially improved by the increment of PC ratio in the casting solution and then it decreased. The membrane with 70% PC exhibited the highest flux, maximum current efficiency, and minimum energy consumption. However, the selectivity of this membrane was low compared with the other prepared membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
997.
This study aims to examine atmospheric corrosivity, corrodants, and corrosion products of southeastern coastal area of China–Pakistan Economic Corridor as per ISO protocols 9223 and 9225, and ASTM standards G1, G50, G140-02, D4458-94, and D2010. Test sites are located at National Institute of Oceanography (NIO) and Karachi Port Trust (KPT) at the banks of the Arabian Sea. Electrogalvanized mild steel test coupons were exposed, and levels of corrodants (sulfur dioxide, chloride, and time of wetness) were measured for a period of 24 months, from May 2014 to May 2016. Corrosivity category C5+ is established in terms of the corrosion rate for both NIO and KPT test stations, which does not coincide with the corrosivity category C5 ascertained by employing environmental characteristics and atmospheric corrodants. Corrosion kinetic parameter “n” and correlation coefficient (R2) are 0.71 and 0.97 for NIO and 0.96 and 0.97 for KPT, respectively. Scanning electron microscopy/energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction spectroscopy have corroborated the presence of simonkolleite and hydrozincite, zinc oxide, zinc hydroxychloride, and zinc in corrosion products at both test sites. 相似文献
998.
999.
F. Shahbaz?Tehrani V. Daadmehr A. T. Rezakhani R. Hosseini?Akbarnejad S. Gholipour 《Journal of Superconductivity and Novel Magnetism》2012,25(7):2443-2455
Ferrite nanocrystals are an interesting material due to their rich physical properties. Here we add non-magnetic dopants Zn and Cu to nickel ferrite nanocrystals, Ni1?x M x Fe2O4 (0??x??1, M=Cu, Zn), and study how relevant properties of the samples are modified accordingly. Basically, these dopings cause a rearrangement of Fe+3 ions into the two preexisting octahedral and tetrahedral sites. In fact, this, we show, induces pertinent magnetic properties of the doped samples. In the case of the Cu-doping, the Jahn?CTeller effect also emerges, which we identify through the Fourier Transform Infra-Red Spectroscopy of the samples. Moreover, we show an increase in the lattice parameters of the doped samples, as well a superparamagnetic behavior for the doped samples is shown, while the Jahn?CTeller effect precludes a similar behavior in the CuFe2O4 nanocrystals. The influences of Zn and Cu substitutions are investigated on the optical properties of nickel ferrite nanocrystals by photoluminescence measurement at room temperature. 相似文献
1000.
A facile and one-pot strategy for the preparation of novel diamino-functionalized hollow siliceous spheres (DAF-HSS) is suggested. Field-emission scanning electron microscopy (FE-SEM) images of DAF-HSS showed a monodispersed hollow sphere morphology. Also, TEM images revealed that the DAF-HSS has a porous structure with parallel semi-long-range channels. DAF-HSS material was used as an adsorbent for the removal of hazardous monocationic dyes in aqueous solution. Neutral red (NR) and crystal violet (CV) were selected as model compounds. Isotherm and kinetic studies were carried out and their different linear forms were applied and compared. The equilibrium data fitted better with the Langmuir model. 相似文献